The present invention provides an improvement to the locking handle shown in my U.S. Pat. No. 4,002,386, incorporated herein by reference. This previous handle has end portions lockably engaging a card cage rack to prevent removal of a circuit card module to which the handle is secured. The circuit card module is removed by pulling the handle to flex the latter and release its end portions from engagement with the card cage.
Upon reinsertion of the circuit card module, the handle had to remain in a bowed position. This forced the operator to push on the raw edge of the circuit card module in order to apply insertion force. This has become particularly objectionable to an operator installing many units, and can be painful.
One attempt to obviate user engagement of a raw circuit card module edge involved the use of a non-locking handle, e.g., FIG. 7 of said patent. Electrical connectors were added at the back of the card cage to engage all connector pins on the circuit card, whether or not in use, to secure the modules. This alternative was not entirely satisfactory because heavier modules tended to work loose. Furthermore, positive locking was needed on critical modules.
In another proposal, a non-locking handle was used to avoid user engagement of a raw circuit card module edge, and a spring retainer clip was added to afford locking. The clip was wedged between the module and the card cage retaining lip, and this clip required flexing in order to release the unit. While this did solve the problem, such solution was too costly because of the part cost of the clip and the labor to incorporate it.
The present invention evolved from efforts to eliminate the additional cost of the clip, and to obtain a simpler solution to the problem of user engagement of a raw circuit card module edge. An additional objective was that the new handle adapt to existing circuit card modules and their mounting hole pattern.
The present invention meets these and other objectives in solving the above noted problem, and does so in a particularly simple and efficient manner.